It is known that yaw controlling of an aircraft is mainly ensured by a rudder jointed to a vertical stabilizer, being able to rotate in two opposite rotating directions between an aerodynamically neutral position and a maximum rotation breakpoint. To this end, the rudder is controlled by a mobile commanding system (directional crossbar) available to the pilot of the aircraft. This system is generally provided with two pedals which, upon their respective depressions, result in the system being moved in two opposite directions associated respectively with two opposite rotating directions of the rudder. In particular, this directional crossbar controls the rotation of the rudder so that the extent of the rotation of the rudder depends on the extent of the movement of the directional crossbar. Thus, depressing the right pedal, for instance, results from the pilot's intention to generate a yaw moment tending to move the nose of the aircraft to the right, such a moment being achieved by a deflection to the right of the rudder. Thus, when the pilot of the aircraft wishes to correct the lateral trajectory of the aircraft, he can act on the directional crossbar with the purpose of implementing the rudder.
It is also known that it could be provided, when the speed of such an aircraft exceeds a limitation speed threshold, to limit the rotation of the rudder inversely proportionally to the speed of the aircraft, with the purpose of limiting the constraints said aircraft is submitted to at a high speed and, thus, allowing yaw maneuvers to be achieved, including at a high speed.
Thus, when the speed of the aircraft is lower than this limitation speed threshold, if the pilot moves one of the pedals of the directional crossbar until one of the maximum rotation breakpoints of the rudder is reached (in one of the two rotating directions of said rudder), the directional crossbar has itself reached a breakpoint. On the other hand, when the speed of the aircraft is at least equal to this limitation speed threshold, if the pilot moves one of the pedals of the directional crossbar until one of the maximum rotation breakpoints of the rudder is reached (in one of the rotating directions of said rudder), he is still able to move the directional crossbar. In such a case, the movement of the directional crossbar by the pilot could overcome the position of the latter corresponding to the maximum rotation breakpoint of the rudder in one of the rotating directions of said rudder, and the pilot could therefore generate an over-command at the level of said rudder.
It should however be noticed that, when the speed of the aircraft is higher than this limitation speed threshold, if the pilot has beforehand moved one of the pedals of the directional crossbar so that the movement of the directional crossbar overcomes the position of the latter corresponding to the maximum rotation breakpoint in one of the rotating directions of the rudder, with the purpose to carry out, thru an over-command, a yaw maneuver in this same direction, it is possible that the latter suddenly wishes to carry out an opposite yaw maneuver, that is in the other direction, also thru an over-command. To this end, the pilot moves the other pedal of the directional crossbar so that the movement of said directional crossbar overcomes the position thereof corresponding to the maximum rotation breakpoint in the opposite rotating direction of the rudder.
Now, upon such a sudden inversion of the position of the rudder (from one of the maximum rotation breakpoints of the rudder to the other, the aircraft undergoes excessive charges at the level of the vertical stabilizer, linked to too a quick variation of the rotation amplitude of the rudder.
The object of the present invention therefore aims at preventing such a risk for the aircraft upon a yaw maneuver.